Rainer B, Frimmel C, Sumann G, Brugger H, Kinzl JF, Lederer W. Correlation between avalanche emergencies and avalanche danger forecast in the alpine region of Tyrol. Eur J Emerg Med 2008; 15: 43-7.
Department of Anaesthesiology and Critical Care Medicine, Division of Psychosocial Medicine, Innsbruck Medical University, Innsbruck, Austria.
OBJECTIVE: We investigated whether frequency of avalanche accidents corresponds with the danger assessment given in avalanche hazard tables and with topographic factors of the avalanche origin. METHODS: A retrospective review of official avalanche surveillance data and of medical reports from helicopter-based emergency medical systems was conducted. RESULTS: Most victims involved in avalanche accidents are ski tourers and off-piste skiers, about 90% are male, and age ranges from 10 to more than 70 years. Sixty-seven percent of accidents occurred when moderate and considerable danger was forecast. In 94.0% of accidents avalanches were triggered by victims themselves or by nearby recreationists; 32.6% of avalanche slides occurred on extremely steep slopes at gradients exceeding 40 degrees . Overall incidence of accidents before noon was 25.0%. Professional stand-by avalanche parties significantly contributed to rescuing avalanche victims, but the chance of survival is diminished when arrival was delayed. All patients who were able to free themselves from avalanche burial survived. Of those rescued by companions, 78.0% survived compared with only 10.0% of those rescued by organized rescue teams (P<0.001). CONCLUSION: Frequency of avalanche emergencies associated with outdoor leisure activities does not correspond with the danger forecast in avalanche hazard bulletins. There is need of a modified and regionally adjusted grading that makes allowance for experience and individual behavior of recreationists going in for backcountry leisure activities.

Hohlrieder M, Mair P, Wuertl W, Brugger H. The impact of avalanche transceivers on mortality from avalanche accidents. High Alt Med Biol. 2005; 6: 72-7.
Department of Anesthesiology and Critical Care Medicine, University Hospital Innsbruck, Innsbruck, Austria. matthias.hohlrieder@uibk.ac.at
Rapid extrication is the most important determinant of survival in avalanche victims. To facilitate rapid localization of avalanche victims by uninjured companions, avalanche transceivers are widely used during off-piste and backcountry activities. Despite their widespread use, the influence of transceivers on survival probability in avalanche accidents is controversial. The aim of this retrospective study was to analyze the influence of transceivers on the mortality of avalanche victims. There were 194 accidents in Austria from 1994 to 2003, involving 278 totally buried victims, which were analyzed. Avalanche transceivers were used by 156 (56%) victims and were associated with a significant reduction in median burial time from 102 to 20 min (p < 0.001), as well as a significant reduction in mortality from 68.0% to 53.8% (p = 0.011). This reduction was due to a decrease in mortality during backcountry activities involving ski tourers in free alpine areas (from 78.9% to 50.4%, p < 0.001). Transceivers did not reduce mortality during off-piste activities beside or near organized ski slopes (67.7% with versus 58.5% without transceiver, not significant). Mortality of persons using a transceiver is significantly higher if burial depth exceeds 1.5 m. Despite a significant reduction, mortality still exceeds 50% even with the use of transceivers. Therefore, in addition to the use of emergency equipment like transceivers, avalanche avoidance measures are critically important. The fairly modest influence of the use of transceivers on survival probability may be due to the highly efficient mountain rescue service in the Austrian Alps. In remote areas the reduction in mortality will probably be far more pronounced.

Brugger H, Falk M, Adler-Kastner L [Avalanche emergency. New aspects of the pathophysiology and therapy of buried avalanche victims] [Article in German] Wien Klin Wochenschr. 1997; 109: 145-59.
Bergrettungsarzt im Alpenverein Südtirol, Mitglied der Internationalen Kommission für Alpine Notfallmedizin, Bruneck, Italien.
A series of investigations on the pathophysiology and management of persons buried in an avalanche has been undertaken over the past few years in response to increased awareness of the importance of emergency medical treatment of avalanche victims and the fact that the high mortality rate has not decreased in spite of the improvement in rescue techniques. This paper is the very first review of the problems encountered in avalanche disasters. The developments over the past 20 years, in particular, are summarized and discussed. Furthermore, current opinions and recommendations on optimal rescue procedure, as well as the prevention of such emergencies are presented. Precise assessment of the survival probability after burial under an avalanche and recognition of the prognostic importance of an air pocket, but only limited role of hypothermia, provide the basis for new concepts governing therapy and triage by the emergency doctor. Resulting guidelines have been endorsed by the Emergency Medicine Subdivision of the International Commission of the Alpine Rescue Services (ICAR) and these recommendations are intended for implementation by organised rescue teams in order to reduce secondary deaths following successful extrication of victims from the avalanche masses. However, the chance of being rescued alive depends primarily on the rapidity of extrication, i.e. how quickly the rescue teams are alerted and transported to the disaster area in the first instance, then how quickly the victims are located and extricated. In order to reduce the mortality additional preventive measures must be introduced to avoid complete burial if possible, or appreciably hasten the rescue procedure. The very steep drop ("fatal kink") in survival probability as from 15 minutes after burial underlines the absolute necessity of the mastery of efficient rescue procedure by uninjured companions. Improvement of the technical developments for the avoidance of total burial (avalanche air bag) and optimization of the electronic location (transceiver) of buried skiers by uninjured companions are essential future requirements. Nonetheless, primary prevention remains of paramount importance in governing decision making by offpiste skiers. Correct assessment of the inherent risks according to the prevailing circumstances and strict adherence to safety rules take precedence over all other considerations.

Hohlrieder M, Brugger H, Schubert HM, Pavlic M, Ellerton J, Mair P. Pattern and severity of injury in avalanche victims. High Alt Med Biol 2007; 8: 56-61.
Department of Anesthesiology and Critical Care Medicine, Medical University Innsbruck, Innsbruck, Austria. matthias.hohlrieder@i-med.ac.at
In avalanche accidents, the significance of major trauma as a cause of morbidity and mortality is controversial. The aim of this retrospective study is to determine the severity and pattern of injury in avalanche victims admitted to the University Hospital of Innsbruck between 1996 and 2005. A total of 49 significant injuries were found in 105 avalanche victims; the most frequent were of the extremities (n = 20), the chest (n = 18), and the spine (n = 7). In contrast, cerebral (n = 2), abdominal visceral (n = 1), and pelvic trauma (n = 1) were rare. The severity of injury was minor or moderate in most patients, with only 9 (8.6%) being severely or critically injured. Of 105 (34.3%) avalanche victims, 36 died. Autopsy was performed in 30 of 36 nonsurvivors. The cause of death in the remaining 6 victims was concluded from clinical, radiological, and electrophysiological findings. Trauma was responsible for deaths of only 2 avalanche victims (5.6%); both had cervical spine fractures with dislocation leading to death. One death was due to hypothermia, whereas the remaining 33 fatalities (91.7%) were due to asphyxia. The incidence of life-threatening or lethal trauma was well below 10%. Asphyxia is by far the most important reason for death. Deaths from trauma were solely due to isolated cervical injuries, demonstrating that the cervical spine may be a region at particular risk in avalanche victims.

Page CE, Atkins D, Shockley LW, Yaron M. Avalanche deaths in the United States: a 45-year analysis. Wilderness Environ Med. 1999; 10: 146-51.
Denver Health Medical Center, Division of Emergency Medicine, CO 80204, USA.
OBJECTIVE: To describe the demographic characteristics and patterns of death of persons killed in snow avalanches over a 45-year study period. METHODS: The national avalanche database was the source of data in this retrospective, descriptive study. RESULTS: A total of 440 victims were killed in 324 fatal avalanches, of which 87.7% were fully buried, 4.7% were partially buried, and 7.6% were not buried. The average age was 27.6 +/- 10.6 years, and 87.3% were men. Victims who died included climbers (25.5%), backcountry skiers (22.7%), out-of-bounds skiers (10.0%), snowmobilers (6.8%), in-bounds skiers (5.2%), residents (4.5%), ski patrollers (3.6%), workers (3.6%), and motorists (3.0%). Over the 45-year study period there appear to be decreases in the deaths of in-bounds skiers, highway workers, and motorists. Increasing fatalities were observed among out-of-bounds skiers, snowmobilers, ski patrollers, and backcountry skiers. Most deaths occurred in Colorado (33.0%), Washington (13.2%), and Alaska (12.0%). CONCLUSIONS: Avalanche fatalities have increased over the last 45 years. Climbers, backcountry skiers, out-of-bounds skiers, and more recently snowmobilers constitute the majority of the victims. The decrease in deaths among groups that benefit from avalanche control programs supports the benefit of avalanche prevention strategies. Further study is needed to assess the impact of avalanche safety education for individuals who travel in remote and uncontrolled terrain.

Strohm PC, Köstler W, Hammer T, Südkamp NP. [Avalanche emergency and accidental hypothermia] Unfallchirurg. 2003; 106: 343-7. [Article in German]
Department für Orthopädie und Traumatologie, Klinik für Traumatologie, Uniklinikum, Freiburg. strohm@ch11.ukl.uni-freiburg.de
The importance of emergency medical treatment for avalanche victims in the pre-clinical and clinical sector is still real. Based on new investigations, guidelines for triage have been endorsed by the International Commission of the Alpine Rescue Services (ICAR) to reduce secondary deaths following the successful extrication of victims from the avalanche mass. Although hypothermia plays a secondary role in the total mortality of avalanche victims, the most important task if extrication lasts 35 min or more is the professional treatment of hypothermia. Avalanche emergencies in the southern part of the Black Forest are quite rare. In February 2002 one avalanche victim in this region survived despite a statistically bad prognosis. Based on the current literature, we provide an algorithm which conforms with the ICAR guidelines for emergency personnel and describe the possibilities and standard stage dependent treatment in cases of accidental hypothermia.

Brugger H, Sumann G, Meister R, Adler-Kastner L, Mair P, Gunga HC, Schobersberger W, Falk M. Hypoxia and hypercapnia during respiration into an artificial air pocket in snow: implications for avalanche survival. Resuscitation. 2003; 58: 81-8.
Mountain Rescue Service provided by the South Tyrolean Alpine Association, International Commission for Mountain Emergency Medicine, Europastrasse 17, I-39031 Bruneck, Italy. brugger.med@pass.dnet.it
Snow avalanche case reports have documented the survival of skiers apparently without permanent hypoxic sequelae, after prolonged complete burial despite there being only a small air pocket on extrication. We investigated the underlying pathophysiological changes in a prospective, randomised 2 x 2 crossover study in 12 volunteers (28 tests) breathing into an artificial air pocket (1- or 2-l volume) in snow. Peripheral SpO2, ETCO2, arterialised capillary blood variables, air pocket O2 and CO2, snow density, and snow conditions at the inner surface of the air pocket were determined. SpO2 decreased from a median of 99% (93-100%) to 88% (71-94%; P<0.001) within 4 min of breathing into the air pocket; the reduction was greater at 1 l, than 2 l, volume air pocket (P=0.013, intention to treat P=0.003) and correlated to snow density (r=0.50, P=0.021, partial correlation coefficient). ETCO2 rose simultaneously from median 5.07 kPa (3.47-6.93 kPa) to 6.8 kPa (5.87-8.27 kPa; P<0.001), with consequent respiratory acidosis. Despite premature interruption due to hypoxia (SpO2</=75%) in 17 of 28 tests (61%), a respiratory steady state prevailed in five tests until protocol completion (30 min). We conclude that the degree of hypoxia following avalanche burial is dependent on air pocket volume, snow density and unknown individual personal characteristics, yet long-term survival is possible with only a small air pocket. Hence, the definition of an air pocket, "any space surrounding mouth and nose with the proviso of free air passages" is validated as the main criterion for triage and management of avalanche victims. Our experimental model will facilitate evaluating the interrelation between volume and inner surface area of an air pocket for survival of avalanche victims, whilst the present findings have laid the basis for future investigation of possible interactions between hypoxia, hypercapnia, and hypothermia (triple H syndrome) in snow burial.

Brugger H, Etter HJ, Zweifel B, Mair P, Hohlrieder M, Ellerton J, Elsensohn F, Boyd J, Sumann G, Falk M. The impact of avalanche rescue devices on survival. Resuscitation. 2007; 75: 476-83.
International Commission for Mountain Emergency Medicine, Innsbruck Medical University, Europastrasse 17, I-39031 Bruneck, Italy. brugger.med@pass.dnet.it
BACKGROUND: Within Europe and North America, the median annual mortality from snow avalanches between 1994 and 2003 was 141. There are two commonly used rescue devices: the avalanche transceiver, which is intended to speed up locating a completely buried person, and the avalanche airbag, which aims to prevent the person from being completely buried. OBJECTIVE: This retrospective study aimed to evaluate whether these avalanche rescue devices had an effect on mortality. METHODS: The study population was 1504 persons who were involved in 752 avalanches either in Switzerland from 1990 to 2000 and from 2002 to 2003 (1296 persons, 86.2%) or in Austria from 1998 to 2004 (208 persons, 13.8%). RESULTS: Persons equipped with an avalanche airbag had a lower chance of dying (2.9% versus 18.9%; P=0.026, OR 0.09, n=1504). In persons who were completely buried, without visible or audible signs at the surface and who did not rescue themselves (n=317), we found a lower median duration of burial (25min versus 125min; P<0.001) and mortality (55.2% versus 70.6%; P<0.001, OR 0.26) in those using an avalanche transceiver than in those not using the device. CONCLUSIONS: Our data showed that both the avalanche airbag and the avalanche transceiver reduce mortality. However, to improve the evaluation of rescue devices in the future, the data collection procedures should be reviewed and prospective trials should be considered, as the reliability of retrospective studies is limited.

Dorn W, Matter P. [Case reports of Davos avalanche accidents 1972/73-1987/88] Z Unfallchir Versicherungsmed. 1993; Suppl 1: 255-61. [Article in German]
Spital Davos.
The main aim of this analysis was to study from different point of views the registered accidents in whom people were involved caused by avalanches during the winter-periods 1972/73 to 1987/88. As a result of this study a Swiss register for all accidents caused by avalanches was produced. The final goal of the register is to compile centralized a most complete database on all the details of either the avalanche victims or of the accidents themselves. This database is to be used for further analysis of the accidents in order to provide more background information to discuss and to improve the primary care of these patients.

Grosse AB, Grosse CA, Steinbach LS, Zimmermann H, Anderson S. Imaging findings of avalanche victims. Skeletal Radiol. 2007; 36: 515-21.
Department of Diagnostic, Pediatric and Interventional Radiology, University Hospital of Berne, Inselspital, Freiburg Strasse, 3010, Berne, Switzerland. alexandragrosse@gmx.at
OBJECTIVE: Skiing and hiking outside the boundaries remains an attractive wilderness activity despite the danger of avalanches. Avalanches occur on a relatively frequent basis and may be devastating. Musculoskeletal radiologists should be acquainted with these injuries. DESIGN AND PATIENTS: Fourteen avalanche victims (11 men and 3 women; age range 17-59 years, mean age 37.4 years) were air transported to a high-grade trauma centre over a period of 2 years. RESULTS: Radiographs, CT and MR images were prospectively evaluated by two observers in consensus. Musculoskeletal findings (61%) were more frequent than extraskeletal findings (39%). Fractures were most commonly seen (36.6%), involving the spine (14.6%) more frequently than the extremities (9.8%). Blunt abdominal and thoracic trauma were the most frequent extraskeletal findings. CONCLUSION: A wide spectrum of injuries can be found in avalanche victims, ranging from extremity fractures to massive polytrauma. Asphyxia remains the main cause of death along with hypoxic brain injury and hypothermia.

Silverton NA, McIntosh SE, Kim HS. Avalanche safety practices in Utah. Wilderness Environ Med 2007; 18: 264-70.
Division of Emergency Medicine, University of Utah, Salt Lake City, UT, USA.
OBJECTIVE: Avalanche fatalities occur on a yearly basis in Utah. The purpose of this study was to assess avalanche safety practices of different backcountry users in Utah and to identify groups that can be targeted for avalanche safety education. METHODS: We surveyed 353 winter backcountry users to determine the percentage of participants in each group who were traveling with one or more partners; the percentage who were carrying avalanche transceivers, shovels, probes, or AvaLungs; and the percentage who had taken an avalanche safety course. A measure of minimum safe practice was defined as 1) traveling with a partner, 2) carrying an avalanche transceiver, and 3) carrying a shovel. Participants in this study were backcountry skiers, snowboarders, snowshoers, snowmobilers, and out-of-bounds resort skiers/snowboarders traveling in the Wasatch and Uinta Mountains of Utah during the winter of 2005-06. RESULTS: The percentage of backcountry recreationists traveling with one or more partners was not significantly different (P=.0658) among backcountry skiers, snowboarders, snowshoers, snowmobilers, and out-of-bounds resort skiers/snowboarders. These groups did, however, differ in the percentage who carried avalanche transceivers (P<.0001), shovels (P<.0001), probes (P<.0001), and AvaLungs (P=.0020), as well as in the percentage who had taken an avalanche safety course (P<.0001) and the percentage who were carrying out minimum safe practices (P<.0001). Backcountry skiers showed the highest level of avalanche preparedness, with 98% carrying avalanche transceivers, 98% carrying shovels, 77% carrying probes, 86% having taken an avalanche safety course, and 88% carrying out minimum safe practices. Out of bounds snowboarders were the least prepared with 9% carrying avalanche transceivers, 9% carrying shovels, 7% carrying probes, 33% having taken an avalanche safety course, and 2% carrying out minimum safe practices. CONCLUSIONS: There are significant differences in the avalanche safety practices of the various groups of backcountry travelers in Utah. Backcountry skiers and snowboarders were the most prepared, while snowmobilers, snowshoers, and out-of-bounds skiers/snowboarders were relatively less prepared.

McIntosh SE, Grissom CK, Olivares CR, Kim HS, Tremper B. Cause of death in avalanche fatalities. Wilderness Environ Med 2007; 18: 293-7.
Division of Emergency Medicine, University of Utah, Salt Lake City, UT 84132, USA. scott.ncintosh@hsc.utah.edu
OBJECTIVE: Avalanches pose a life-threatening risk to participants of outdoor winter activities. Determining the causes of death in avalanche fatalities can aid rescue and resuscitation strategies and hopefully improve survival. METHODS: The study population included all avalanche fatalities in Utah from the 1989-90 to 2005-06 winter seasons. The Utah Avalanche Center and Medical Examiner records were reviewed to identify accident circumstances, autopsy findings, and causes of death. RESULTS: Fifty-six avalanche deaths were identified during the study period. Most deaths occurred while participating in recreational backcountry activities; 85.7% of deaths were due to asphyxiation, 8.9% were due to a combination of asphyxiation and trauma, and 5.4% were due to trauma alone. Head injuries were frequent in those killed solely by trauma. CONCLUSIONS: Most avalanche deaths in Utah result from asphyxia. Therefore, most victims are alive in the postavalanche period and have the potential for live recovery. Rescue strategies that employ rapid recovery as well as techniques that prolong survival while buried provide the best means of improving outcome.
Rostrup M, Gilbert M, Stalsberg H. [A snow avalanche in Vassdalen. Medical experiences] Tidsskr Nor Laegeforen 1989; 109: 807-13. [Article in Norwegian]
Of 31 soldiers caught by an avalanche in Northern Norway, one was not buried, 13 were partly buried and 17 were completely buried by the mass of snow. Only one of the completely buried soldiers survived. On admission to hospital after being buried by snow for three hours he had moderate hypothermia. The cause of death in the other 16 was most probably general compression of the body with acute respiratory and circulatory failure. Five of the 13 partly buried had physical traumas. None of the nine attempts at resuscitation succeeded. Self-rescue and rescue by friends were most important to the soldiers who survived. We discuss aspects of the organized rescue operation.

Grissom CK, Radwin MI, Harmston CH, Hirshberg EL, Crowley TJ. Respiration during snow burial using an artificial air pocket. JAMA 2000; 283: 2266-71.
Comment in: JAMA 2000; 283: 2293-4. JAMA 2000; 284: 1242-3; author reply 1243-4. JAMA 2000; 284: 1243; author reply 1243-4.
Pulmonary Division, LDS Hospital, University of Utah, Salt Lake City 84143, USA. ldcgriss@ihc.com
CONTEXT: Asphyxia is the most common cause of death after avalanche burial. A device that allows a person to breathe air contained in snow by diverting expired carbon dioxide (CO2) away from a 500-cm3 artificial inspiratory air pocket may improve chances of survival in avalanche burial. OBJECTIVE: To determine the duration of adequate oxygenation and ventilation during burial in dense snow while breathing with vs without the artificial air pocket device. DESIGN: Field study of physiologic respiratory measures during snow burial with and without the device from December 1998 to March 1999. Study burials were terminated at the subject's request, when oxygen saturation as measured by pulse oximetry (SpO2) dropped to less than 84%, or after 60 minutes elapsed. SETTING: Mountainous outdoor site at 2385 m elevation, with an average barometric pressure of 573 mm Hg. PARTICIPANTS: Six male and 2 female volunteers (mean age, 34.6 years; range, 28-39 years). MAIN OUTCOME MEASURES: Burial time, SpO2, partial pressure of end-tidal CO2 (ETCO2), partial pressure of inspiratory CO2 (PICO2), respiratory rate, and heart rate at baseline (in open atmosphere) and during snow burial while breathing with the device and without the device but with a 500-cm3 air pocket in the snow. RESULTS: Mean burial time was 58 minutes (range, 45-60 minutes) with the device and 10 minutes (range, 5-14 minutes) without it (P=.001). A mean baseline SpO2 of 96% (range, 90%-99%) decreased to 90% (range, 77%-96%) in those buried with the device (P=.01) and to 84% (range, 79%-92%) in the control burials (P=.02). Only 1 subject buried with the device, but 6 control subjects buried without the device, decreased SpO2 to less than 88% (P=.005). A mean baseline ETCO2 of 32 mm Hg (range, 27-38 mm Hg) increased to 45 mm Hg (range, 32-53 mm Hg) in the burials with the device (P=.02) and to 54 mm Hg (range, 44-63 mm Hg) in the control burials (P=.02). A mean baseline PICO2 of 2 mm Hg (range, 0-3 mm Hg) increased to 32 mm Hg (range, 20-44 mm Hg) in the burials with the device (P=.01) and to 44 mm Hg (range, 37-50 mm Hg) in the control burials (P=.02). Respiratory and heart rates did not change in burials with the device but significantly increased in control burials. CONCLUSIONS: In our study, although hypercapnia developed, breathing with the device during snow burial considerably extended duration of adequate oxygenation compared with breathing with an air pocket in the snow. Further study will be needed to determine whether the device improves survival during avalanche burial.

Kaufmann M, Moser B, Lederer W. Changes in injury patterns and severity in a helicopter air-rescue system over a 6-year period. Wilderness Environ Med 2006; 17: 8-14.
Department of Anesthesiology and Critical Care Medicine, Innsbruck Medical University, Innsbruck, Austria. Marc.Kaufmann@uibk.ac.at
OBJECTIVE: To study the influence of current trends in alpine sports on the frequency and types of injuries handled by a helicopter-based emergency medical system (HEMS) in a wilderness mountain region. METHODS: A retrospective review of medical reports at a single emergency helicopter port (Christophorus-1 air rescue) in Innsbruck, Austria, was conducted for comparison between two 3-year periods (1998-2000 and 2001-2003). RESULTS: Comparing the two 3-year periods, the proportion of leisure-time injuries leading to HEMS activation increased, whereas the frequency of life-threatening injuries significantly declined (P = .001). There was significant increase in injuries during mountain hiking and rock climbing (P = .002), during swimming (P = .013), and in avalanches (P = .019). Most injuries (70.1%) were recorded for skiers, and 68.3% involved tourists. During the investigation period, the high National Advisory Committee of Aeronautics scores showed a decreasing trend, whereas Glasgow Coma Scale scores and low National Advisory Committee of Aeronautics scores tended to increase (P = .048). CONCLUSIONS: For the HEMS in this study, there has been an increasing number of calls for help from persons involved in outdoor leisure activities. As the number of life-threatening injuries declines, HEMSs more frequently serve as means of rescue rather than as providers of emergency treatment.

Rostrup M, Gilbert M. [Avalanche accidents] Tidsskr Nor Laegeforen 1993; 113: 1100-2. [Article in Norwegian]
Avdeling for hjertesykdommer, Medisinsk klinikk, Ullevål sykehus, Oslo.
Most avalanche victims die from asphyxia (68%) followed by trauma (13%). Hypothermia is a less common cause of death. Asphyxia may be caused by obstructed airways owing to aspiration of snow, an immobile thorax due to compression by the surrounding snow or lack of diffusion of oxygen through the mass of snow. Clearing airways and quick mobilization of the thorax are of utmost importance in the initial treatment. Cardiopulmonary resuscitation may be required. Unconscious victims without vital signs should be treated in the same way as victims with severe hypothermia.

Brugger H, Falk M.[New perspectives of avalanche disasters. Phase classification using pathophysiologic considerations] Wien Klin Wochenschr 1992; 104: 167-73. [Article in German]
Bergrettungsarzt im Alpenverein Südtirol, Ausbildungsarzt für den Verband Südtiroler Berg- und Skiführer, Italien.
This study comprises an analysis of the data on 332 persons totally buried by avalanches in Switzerland between 1981 and 1989. The survival rate was calculated with the aid of a computer-assisted estimation procedure according to Turnbull. The curve pattern was interpreted according to pathophysiological considerations, on the basis of which the time course of the battle for survival was divided into 4 phases: 1) Survival phase: until 15 minutes after burial under the snow masses. The survival probability amounts to 93% and is, thus, higher than so far assumed. Almost all those buried survived this period of the time provided they were not fatally injured and received first aid. 2) Asphyxia phase: duration of burial under the avalanche from 15 to 45 minutes. The probability of survival sank dramatically during this period from 93% to about 25% (fatal kink of the survival probability curve). Those buried under the snow without an air pocket die of acute asphyxia (the point of no return) and the mortality rate reaches its maximum in this phase. 3) Latent phase: the period as from 45 minutes following the avalanche until the time of rescue. This phase is survived only in the presence of an air pocket. With sufficient oxygen reserves and freedom of thoracic movement a "phase of relative safety" occurs, whereby the survival probability diminishes further only slowly. The first deaths due to hypothermia arise after 90 minutes. 4) Rescue phase: from the time of extrication from the snow until arrival in hospital. There is an increased risk of a fatal outcome during the rescue procedure and immediately afterwards through augmented hypothermia.(ABSTRACT TRUNCATED AT 250 WORDS)

Locher T, Walpoth BH. [Differential diagnosis of circulatory failure in hypothermic avalanche victims: retrospective analysis of 32 avalanche accidents] Schweiz Rundsch Med Prax 1996; 85: 1275-82. [Article in German]
Klinik für Thorax-, Herz- und Gefässchirurgie, Inselspital, Bern.
In avalanche accidents the cause of cardio-respiratory arrest (asphyxia, hypothermia, trauma) is difficult to determine in the field but may be important (high number of victims, limited number of rewarming places). 32 avalanche accidents (16 survivors/16 deaths) were therefore reviewed retrospectively. In 19 patients with cardiorespiratory arrest, asphyxia was frequent (17 patients, 89%) hypothermia was rare (two patients, 11%). The cooling rate between the accident and the arrival at the hospital was 3.0 degrees C/h. (range 0.75-5.8). The core temperature at arrival in the hospital was dependent on the time spent buried under the snow (survivors) and total time (nonsurvivors). The maximal cooling rate under the snow was estimated at 8 degrees C/h. Cardiorespiratory arrest in hypothermic patients without asphyxia seems only to be possible after being buried for at least 1 h. under the snow. Serum potassium was elevated in most cases of asphyxia.

Stepanek J, Claypool DW. GPS signal reception under snow cover: a pilot study establishing the potential usefulness of GPS in avalanche search and rescue operations. 25: Wilderness Environ Med 1997; 8: 101-4.
Emergency Medical Services, Mayo Clinic, Rochester, MN 55905, USA.
Avalanches are one of the major threats to life in high-mountain terrain and account every year for approximately 150 accidents causing injury or death in the United States alone. Every year avalanches cause significant property damages and a death toll of approximately 15 people in the United States. The specific characteristic of the avalanche accident is the extreme importance of getting to the buried victim as soon as, possible to improve survival. Approximately 40% of all buried victims survive 1 hour, and only about 20% survive 2 hours. Newer studies from Europe indicate that the initial survival probability is 92% at 15 minutes, 30% at 35 minutes, 27% at 90 minutes, and finally drops to 3% at 130 minutes. Unless prompt and efficient search and rescue are ensured, the prospect of buried victims is rather grim. Many tools have been used in the past to aid in retrieving buried victims including the avalanche cord, probing techniques, and in more recent time, the use of electronic beacon devices that allow search teams to locate the buried victim. The advent of satellite navigational aids (GPS, GLONASS) makes it possible to determine one's position with remarkable accuracy. We studied the degree to which the GPS satellite signal could penetrate through snow and be received by a commercially available GPS receiver. This information may lead to the development of an additional tool for precise and quick localization of buried victims in avalanche accidents and thus may substantially improve their survival by shortening the search time at the accident site. In this study we used a Motorola Traxar six-channel GPS receiver with amplifier unit connected to an antenna by means of a shielded coaxial cable. The antenna was buried under incremental covers of compact snow, and the reception of the GPS signal was measured at each burial depth: 5 cm, 15 cm, 25 cm, 35 cm, 45 cm, 55 cm, 1 m, and 1.5 m. The variables that were measured included signal quality, number of satellites received by the receiver, and their respective signal strength. A reference reading was taken from the GPS receiver above the testing site before measurements under snow cover were started. The satellite signals were received with good quality and precise readings up to a burial depth of 1 m. Under 1.5 m of snow the receiver was able to lock on only one satellite, making a positional reading impossible. The reception of the GPS signals under snow cover is possible and warrants further study directed toward the development of a search and rescue device using this technology.

Brugger H, Durrer B, Adler-Kastner L, Falk M, Tschirky F. Field management of avalanche victims. Resuscitation. 2001; 51: 7-15.
Alpine Rescue Service provided by the South Tyrolean Alpine Association, International Commission for Alpine Emergency Medicine, Europastrasse 17, I-39031, Bruneck, Italy. brugger.med@pass.dnet.it
The median annual mortality from snow avalanches registered in Europe and North America 1981-1998 was 146 (range 82-226); trend stable in Alpine countries (r=-0.29; P=0.24), increasing in North America (r=0.68; P=0.002). Swiss data over the same period document 1886 avalanche victims, with an overall mortality rate of 52.4% in completely-buried, versus 4.2% in partially-, or non-buried, persons. Survival probability in completely-buried victims in open areas (n=638) plummets from 91% 18 min after burial to 34% at 35 min, then remains fairly constant until a second drop after 90 min. Likewise, survival probability for completely-buried victims in buildings or on roads (n=97) decreases rapidly following burial initially, but as from 35 min it is significantly higher than that for victims in open areas, with a maximum difference in respective survival probability (31% versus 7%) from 130 to 190 min (P<0.001). Standardised guidelines are introduced for the field management of avalanche victims. Strategy by rescuers confronted with the triad hypoxia, hypercapnia and hypothermia is primarily governed by the length of snow burial and victim's core temperature, in the absence of obviously fatal injuries. With a burial time < or =35 min survival depends on preventing asphyxia by rapid extrication and immediate airway management; cardiopulmonary resuscitation for unconscious victims without spontaneous respiration. With a burial time >35 min combating hypothermia becomes of paramount importance. Thus, gentle extrication, ECG and core temperature monitoring and body insulation are mandatory; unresponsive victims should be intubated and pulseless victims with core temperature <32 degrees C (89.6 degrees F) (prerequisites being an air pocket and free airways) transported with continuous cardiopulmonary resuscitation to a specialist hospital for extracorporeal re-warming.

Grossman MD, Saffle JR, Thomas F, Tremper B. Avalanche trauma. J Trauma 1989; 29: 1705-9.
Department of Surgery, University of Utah Medical Center, Salt Lake City 84132.
Medical aspects of avalanche accidents have apparently not been studied in the American literature. Records from the Utah Avalanche Forecasting Center (UAFC) for the period 1982-1987 were reviewed and compared with similar data from Europe and Canada. One hundred forty-five avalanches involving 188 individuals were reported to the UAFC. Ninety-one (48%) people were caught, of whom 21 required medical attention. Twelve of the 91 died (13%) and nine were injured (10%). Eleven of 12 nonsurvivors and four of nine survivors were completely buried. Evidence of major blunt trauma was present in nine of ten nonsurvivors and all nine survivors. Asphyxia and blunt trauma were the most common causes of death; hypothermia appeared to have played only a minor role. These findings were similar to results obtained in Europe and Canada.

Johnson SM, Johnson AC, Barton RG. Avalanche trauma and closed head injury: adding insult to injury. Wilderness Environ Med 2001; 12: 244-7.
Department of Surgery, University of Utah School of Medicine, Salt Lake City, USA. johnson_sid@yahoo.com
OBJECTIVE: The incidence of fatal closed head injury (CHI) and nonfatal CHI causing an altered level of consciousness in avalanche victims is unknown. The purpose of this study was to assess the incidence and potential significance of CHI in avalanche-related deaths. METHODS: The records of the state medical examiner and hospital records of all victims killed in avalanches in the state of Utah from October 1, 1992 through April 30, 1999 were reviewed for a cause of death and for the presence of CHI. Closed head injury was described as "present" or "severe," depending on whether the degree of CHI was sufficient to have caused or directly contributed to death, as determined by the medical examiner. RESULTS: In this review, 28 avalanche-related deaths were identified, of which 22 (79%) were due to asphyxia. Seventeen victims (61%) had evidence of some degree of CHI. Six victims (21%) had evidence of severe CHI. One of 7 snowmobile riders sustained a severe CHI, whereas 4 of 16 skiers or snowboarders sustained a severe CHI (P = not significant). CONCLUSION: Although asphyxiation was the cause of death in most avalanche victims, evidence of CHI was present in 61% of the cases studied. While avalanche-associated CHI may not be sufficient to cause death in many cases, a depressed level of consciousness might render a victim incapable of self-rescue and predispose to asphyxia. Helmet use may help prevent avalanche-associated CHI and thus be a useful safety adjunct.

Buser O, Etter HJ, Jaccard C. [Probability of dying in an avalanche] Z Unfallchir Versicherungsmed 1993; Suppl 1: 263-71. [Article in German]
Eidgenössisches Institut für Schnee- und Lawinenforschung, Davos Dorf.
Of 1,036 people caught in an avalanche and completely buried the burial time and whether they were recovered dead or alive is recorded. The data are used to calculate the likelihood to die in the avalanche as a function of the burial time, using Turnbull's non-parametric method. The result is compared with Brugger's et al for 332 cases. Furthermore the influence on the likelihood of mortality is investigated using further indications to reduce the time interval during which the victim has died.

Tough SC, Butt JC. A review of 19 fatal injuries associated with backcountry skiing. Am J Forensic Med Pathol 1993; 14: 17-21.
Office of the Chief Medical Examiner, Calgary, Alberta, Canada.
A review of circumstances surrounding 19 backcountry deaths in Alberta, Canada, between 1980 and 1991 suggests several factors that increase the risk of injury or death. This study provides a descriptive profile of a fatally injured backcountry skier and the circumstances surrounding his or her death. The individual most likely to suffer a fatal injury while participating in a backcountry ski activity is a 36-year-old man. He is typically an experienced backcountry skier who chooses to ski in areas where the avalanche hazard is known to be moderate to extreme. Delineating the personal characteristics of those at risk for backcountry injury and identifying situations that put them at risk will enable better design of education programs. Targeting high-risk groups may also reduce the incidence of death from this activity.

Furrer M, Erhart S, Frutiger A, Bereiter H, Leutenegger A, Rüedi T. Severe skiing injuries: a retrospective analysis of 361 patients including mechanism of trauma, severity of injury, and mortality. J Trauma 1995; 39: 737-41.
Department of Surgery, Kantonsspital Chur, Switzerland.
All ski accident patients requiring an inhospital treatment at our institute from 1984 to 1992 (n = 2,053) were analyzed retrospectively. The incidence, pattern, and severity of the injuries, as well as the 30-day mortality comparing two time slots (1984 to 1988 and 1989 to 1992) were analyzed for the 361 cases classified as "serious" injuries according to the following definitions and groupings: group 1, multiple trauma (Injury Severity Score > or = 18) and patients with multiple fractures (n = 179; group 2, abdominal or thoracic single trauma (Abbreviated Injury Scale (AIS) score > or = 2, n = 58); and group 3, isolated head injuries (AIS score > or = 2, n = 124). Serious injuries were observed in 19% in the first period compared to 16% in the second period (not significant). Two hundred thirty-eight of 361 patients injured themselves by just falling, while 117 collided with some sort of obstacle like other skiers (45), trees or rocks (27), posts, pylons, barriers (20), and moving objects (25) such as piste machines, ski lifts, automobiles, and in one case a helicopter. Six skiers were caught on the ski run by an avalanche. Comparing the two time periods, trauma circumstances did not change significantly. The number of most severe head injuries (AIS score > or = 4) increased from 11.6 to 19.3% (p < 0.05). The overall mortality increased from 2 to 7% (p < 0.05). Group 2 had the best prognosis with no mortality, while group 3 was rated worst with 8%. Skiing remains a major source of serious trauma in winter resort areas.(ABSTRACT TRUNCATED AT 250 WORDS)

Shephard RJ. Asphyxial death of a young skier. J Sports Med Phys Fitness 1996; 36: 223-7.
School of Physical & Health Education, University of Toronto, Ontario, Canada.
OBJECTIVE: Review of the cause of death in fatal downhill skiing accidents is important to prevention: this report concerns a boy found dead with his head buried in powder snow. EXPERIMENTAL DESIGN: Case history of an 11-year-old boy who was found dead 4 hours following descent of a steep ski slope. SETTING: Treatment by mountain rescue team and hospital emergency room. PATIENT: A boy who was discovered immersed head first in one meter of powder snow, with no sign of an avalanche or struggling, and no vital signs. The differential diagnosis included concussion + asphyxia, cervical injury, loss of consciousness from other causes, and hypothermia. INTERVENTIONS: Standard cardio-pulmonary resuscitation, rewarming by bladder irrigation and extracorporeal circulation. RESULTS: The rectal temperature, initially 29.4 degrees C, fell further to 23.3 degrees C during evacuation in a heated ambulance. On hospital admission, a blood sample showed creatine kinase 5306 units, K+ 16 mM, pH 6.38, PaCO2 223 Torr, and PaO2 67 Torr. There was no ECG rhythm, and radiography revealed pulmonary edema but no cervical malignment. Emergency measures normalized blood gases, but did not restore cardiac action. CONCLUSIONS: Death was caused by asphyxia, secondary to mild concussion. The public needs education on the dangers of deep powder snow. Adventurous skiers should wear helmets, and should not ski alone on steep mountainsides.

Mair P, Kornberger E, Furtwaengler W, Balogh D, Antretter H. Prognostic markers in patients with severe accidental hypothermia and cardiocirculatory arrest. Resuscitation. 1994; 27: 47-54.
Comment in: Resuscitation 1994; 28: 72-3.
Department of Anesthesia and Intensive Care Medicine, University of Innsbruck School of Medicine, Austria.
The aim of this retrospective study was to investigate whether plasma potassium, pH and activated clotting time (ACT), obtained from a central venous blood sample immediately after admission to hospital, could predict outcome in patients with severe accidental hypothermia and cardiocirculatory arrest. Twenty-two patients rewarmed with cardiopulmonary bypass were studied retrospectively (12 patients after avalanche accidents, seven patients after cold water submersion and three patients after prolonged exposure to cold). In 12 patients stable spontaneous circulation could not be restored. In 10 patients stable spontaneous circulation could be restored. Two of these 10 patients survived long-term. Plasma potassium, central venous pH and ACT were clinically useful prognostic markers in hypothermic arrest victims after avalanche accidents: a plasma potassium value exceeding 9 mmol/l, a pH equal to or less than 6.50 or an ACT exceeding 400 s was seen in patients in whom spontaneous circulation could not be restored. Plasma potassium, central venous pH and ACT were of only limited prognostic value in hypothermic arrest victims following cold water submersion or prolonged exposure to cold. In hypothermic arrest victims after cold water submersion a central venous pH as low as 6.51 on admission did not exclude long-term survival. Moderate and severe hyperkalemia in arrest victims after prolonged exposure to cold need not necessarily indicate postmortem autolysis. A decision to continue or terminate resuscitation cannot be based on laboratory parameters. Nevertheless, our data suggest that plasma potassium, central venous pH and ACT on admission can be used to identify hypothermic arrest victims in whom death preceded cooling. If several hypothermic arrest victims are admitted simultaneously after avalanche accidents, these 3 parameters can help not to waste limited cardiopulmonary bypass facilities for patients with no hope of survival.

Stalsberg H, Albretsen C, Gilbert M, Kearney M, Moestue E, Nordrum I, Rostrup M, Orbo A. Mechanism of death in avalanche victims. Virchows Arch A Pathol Anat Histopathol 1989; 414: 415-22.
Department of Pathology, Tromsö, University Hospital, Norway.
The autopsies of 12 victims from two snow avalanches in North-Norway are reported. Supportive evidence from non-autopsied and surviving victims is included. Consistent autopsy findings were prominent lung oedema, moderate cerebral oedema, extreme contraction of the left ventricle, petechiae in the superior vena cava drainage area, and acute congestion in lungs and kidneys. In four cases in whom no resuscitation was attempted, aortic oxygen pressure was in the range expected in pure asphyxial-type deaths in one and in pure cardiac-type deaths in three. No air pocket was seen in front of the mouth and nose in any of the fatal cases. Three fatal cases had fractures. It is concluded that the immediate cause of death in most cases was general body compression with acute respiratory and circulatory failure.

Schmid F. [The pathogenesis of pulmonary edema after being buried by an avalanche] Schweiz Med Wochenschr 1981; 111: 1441-5. [Article in German]
A case of pulmonary edema in a rescued avalanche victim is described. The pathogenesis of this complication involves respiratory and hemodynamic factors which are responsible for the development of a hydrostatic pressure gradient between capillaries and alveoli. The resulting transsudation requires some time after the victim has been buried and probably the appearance of pulmonary edema directly precedes death. This might be one of the reasons why pulmonary edema has rarely been observed. However, such an event can, theoretically, be considered part of the pathophysiological processes in buried avalanche victims. In addition to the usual emergency treatment, therapy should, in the light of this theoretical consideration, also be directed towards normalization of the pressure relationship. This can be accomplished by decreasing the pressure in the lung capillaries and increasing the pressure in the alveoli.

Radwin MI, Grissom CK. Technological advances in avalanche survival. Wilderness Environ Med 2002; 13: 143-52.
Comment in: Wilderness Environ Med 2003; 14: 69-70.
Department of Medicine, Granger Medical Clinic, West Valley City, UT 84120, USA sshinn10@aol.com
Over the last decade, a proliferation of interest has emerged in the area of avalanche survival, yielding both an improved understanding of the pathophysiology of death after avalanche burial and technological advances in the development of survival equipment. The dismal survival statistics born out of the modern era of winter recreation unmistakably reveal that elapsed time and depth of burial are the most critical variables of survival and the focus of newer survival devices on the market. Although blunt trauma may kill up to one third of avalanche victims, early asphyxiation is the predominant mechanism of death, and hypothermia is rare. A survival plateau or delay in asphyxiation may be seen in those buried in respiratory communication with an air pocket until a critical accumulation of CO2 or an ice lens develops. The newest survival devices available for adjunctive protection, along with a transceiver and shovel, are the artificial air pocket device (AvaLung), the avalanche air bag system (ABS), and the Avalanche Ball. The artificial air pocket prolongs adequate respiration during snow burial and may improve survival by delaying asphyxiation. The ABS, which forces the wearer to the surface of the avalanche debris by inverse segregation to help prevent burial, has been in use in Europe for the last 10 years with an impressive track record. Finally, the Avalanche Ball is a visual locator device in the form of a spring-loaded ball attached to a tether, which is released from a fanny pack by a rip cord. Despite the excitement surrounding these novel technologies, avalanche avoidance through knowledge and conservative judgment will always be the mainstay of avalanche survival, never to be replaced by any device.

Radwin MI, Grissom CK, Scholand MB, Harmston CH. Normal oxygenation and ventilation during snow burial by the exclusion of exhaled carbon dioxide. Wilderness Environ Med 2001; 12: 256-62.
Department of Medicine, The University of Utah Health Sciences Center, Salt Lake City, USA. sshinn10@aol.com
OBJECTIVE: To confirm that the accumulation of exhaled carbon dioxide (CO2) is the principal cause of nonmechanical asphyxiation during avalanche burial by demonstrating that complete exclusion of exhaled CO2 during experimental snow burial results in normal oxygenation and ventilation utilizing the air within the snowpack. METHODS: In the experimental group, 8 healthy volunteers (mean age 32 years, range 19-44 years) were fully buried up to 90 minutes in compacted snow with a density ranging from 300 to 680 kg/m3 at an elevation of 2385 m. The 6 men and 2 women breathed directly from the snow utilizing a device containing no air pocket around the inhalation intake, in addition to an extended exhalation tube running completely out of the snowpack to remove all exhaled CO2. Continuous physiologic monitoring included oxygen saturation, end-tidal CO2, inspired CO2, electrocardiogram, rectal core temperature, and respiratory rate. As controls, 5 of the 8 subjects repeated the study protocol breathing directly into a small, fist-sized air pocket with no CO2 removal device. RESULTS: In the experimental group, the mean burial time was 88 minutes, despite the absence of an air pocket. No significant changes occurred in any physiologic parameters in this group compared to baseline values. In contrast, the controls remained buried for a mean of 10 minutes (P = .003) and became significantly hypercapnic (P < .01) and hypoxic (P < .02). CONCLUSIONS: There is sufficient oxygen contained within a densified snowpack comparable to avalanche debris to sustain normal oxygenation and ventilation for at least 90 minutes during snow burial if exhaled CO2 is removed. The prolonged oxygenation observed during CO2 exclusion is irrespective of the presence of an air pocket.

Johnsen BH, Eid J, Løvstad T, Michelsen LT. Posttraumatic stress symptoms in nonexposed, victims, and spontaneous rescuers after an avalanche. J Trauma Stress 1997; 10: 133-40.
Department of Biological and Medical Psychology, University of Bergen, Norway.
A company from the Norwegian Army was investigated 2 weeks and 4 months after they were hit by an avalanche during a winter exercise. The subjects were divided into victims, spontaneous rescuers, and nonexposed subjects. The results showed that exposed subjects (victims and rescuers) reported higher levels of symptoms compared to nonexposed subjects. No differences were found among exposed subjects. The level of symptoms was also higher than comparable previous research both on victims and professional rescuers or nonprofessionals assigned a role as rescuers. All groups showed decrement in symptoms on the 4-month follow-up.